MAPPING OF VASCULAR DENDRITIC CELLS IN ATHEROSCLEROTIC ARTERIES SUGGESTS THEIR INVOLVEMENT IN LOCAL IMMUNE-INFLAMMATORY REACTIONS

Objective: We previously demonstrated that vascular dendritic cells (V DCs) are present in the intima of large arteries and that their number s are increased in atherosclerotic lesions. This study was undertaken to determine whether VDC are involved in immune-mediated reactions in atherogenesis. Methods: Specimens of carotid artery and aorta were obt ained at operation. VDCs were identified with anti-CD1a or with S-100. Co-localisation of VDCs with different intimal cells, including T-cel ls and macrophages, was studied using a double immunostaining procedur e. In areas where the co-localising cells were detected, the peculiari ties of expression of HLA-DR, ICAM-1, VCAM-1 were examined. Results: I n all the atherosclerotic plaques, VDCs were seen in contact with T-ce lls, but these co-localising cells were irregularly distributed and we re mainly found in zones of neovascularisation containing inflammatory infiltrates. In other areas, T-cell/VDC co-localisation was rarely de tected but VDCs were often found in contact with macrophages. VDCs wer e detected also in the media beneath atherosclerotic lesions and in th e adventitia, where they were mostly around vasa vasorum, especially i n areas exhibiting signs of acute inflammation. In these areas VDCs ex pressed ICAM-1, VCAM-1 and were in contact with T-cells. In both plaqu es and in the adventitia, the areas with co-localising VDCs and T-cell s corresponded to the areas with HLA-DR expression. Conclusions: The r esults suggest that VDCs are involved in T-cell activation in atheroge nesis. There are two regions within the arterial wall where VDC/T-cell co-localisation mostly occurs, namely, in zones of neovascularisation containing inflammatory infiltrates located within atherosclerotic le sions, and in areas with inflammatory infiltrates around vasa vasorum in the adventitia. Possibly, some intimal VDCs migrate through the med ia and adventitia to adjacent lymph nodes where they present atheroscl erosis associated antigens. We also speculate that VDC/macrophage cont acts are essential in processing immune information in atherogenesis. (C) 1998 Elsevier Science B.V.